A cellular radio access network is a collection of cells that each includes at least one base station capable of transmitting and relaying signals to subscribers' mobile nodes. A “cell” generally denotes a distinct area of a mobile network that utilizes a particular frequency or range of frequencies for transmission of data. A typical base station is a tower to which are affixed a number of antennas that transmit and receive the data over the particular frequency. Mobile nodes, such as cellular or mobile phones, smart phones, camera phones, personal digital assistants (PDAs), and laptop computers, may initiate or otherwise transmit a signal at the designated frequency to the base station to initiate a call or data session and begin transmitting data.
Mobile service provider networks convert cellular signals, e.g., Time Division Multiple Access (TDMA) signals, Orthogonal Frequency-Division Multiplexing (OFDM) signals or Code Division Multiple Access (CDMA) signals, received at a base station from mobile nodes into Internet protocol (IP) packets for transmission within packet-based networks. A number of standards have been proposed to facilitate this conversion and transmission of cellular signals to IP packets, such as a general packet radio service (GPRS) standardized by the Global System for Mobile Communications (GSM) Association, a Universal Mobile Telecommunications System (UMTS), an evolution of UMTS referred to as Long Term Evolution (LTE), as well as other standards proposed by the 3rd Generation Partnership Project (3GPP), 3rd Generation Partnership Project 2 (3GGP/2) and the Worldwide Interoperability for Microwave Access (WiMAX) forum.
A typical mobile service provider network, or “mobile network,” includes a core packet-switched network, a transport network, and one or more radio access networks (RANs). The core packet-switched network for the mobile network establishes logical connections, known as bearers, among the many service nodes on a path between a mobile node attached to one of the radio access networks and a packet data network (PDN). The service nodes then utilize the bearers to transport subscriber data traffic exchanged between the mobile node and the PDN, which may include, for example, the Internet, an enterprise intranet, a layer 3 VPN, and a service provider's private network. Various PDNs provide a variety of packet-based data services to mobile nodes to enable the mobile nodes to exchange service data with application or other servers of the PDNs.
The GPRS Tunneling Protocol (GTP) enables devices of one or more mobile networks to establish GTP-based tunnels for exchanging packets between service nodes (e.g., GPRS Support Nodes (GSNs)) in the mobile network backbone. In the control plane, GTP specifies a tunnel control and management protocol, GTP-C(control), which allows a service node to provide packet data network access for a mobile node associated with a subscriber. The mobile networks use GTP-C signaling to create, modify and delete GTP-U(ser data) tunnels that constitute a bearer for a subscriber session and are used by the service nodes to transport subscriber data traffic for the subscriber.